Rotary pump



n 1941. w. w. DAVIDSON 2,246,275

ROTARfi PUMP Filed July '51, 1936 4 Sheets-Sheet 1 June 17, 1941. w, w.DAVIDSON ROTARY PUMP Filed July 51, 1936 4 Sheets-Sheet 5 r 6 g1 Qww \NNW ww NN 2 4 W m +1 W M 3m Ww \N w mm June 17, 1941. w, w. DAVIDSON 7ROTARY PUMP Filed July 31, 1936 4 Sheets-Sheet 4 Patented June'17, 194TUNITED STATES PATENT OFFICE ROTARY PUMP I William Ward Davidson,Chicago, 11]. Application July 31, 1936, Serial No. 93,633

3 Claims.

This invention relates to improvements in rotary pumps or compressors ofall kinds but particularly to those designed and adapted for use as gascompressors in small refrigerating plants such as are now commonly usedin house refrigerators.

A principal object of the invention is to provide a rotary compressor orpump, combined with a motor for operating same, which shall be of themost simple construction and which shall combine in one rotatablesunitthe rotatable part of the compressor and'the rotatable part of themotor.

A further object of the invention is to provide a combined compressorand motor in which the overall axial dimension shall be reduced to thatrequired for the compressor.

A further object is to provide a combined compressor and motor arrangedin a sealed casing of minimum dimensions and automatic means forcontinuously oiling the bearings and opposed movable surfaces of thecompressor.

The invention includes an electric motor for driving the compressor andhaving an enlarged rotor within which the compressor is arranged, to bedriven thereby, and which construction results in a compressor ofminimum height and high efficiency.

The invention also includes the arrangement of the compressor, the rotorof the motor and the statoror field of the motor all in substantially asingle plane and preferably in a horizontal plane with the axis ofrotation of the compressor arranged vertically.

It should be understood that many of the features of the invention arecapable of incorpora-,

tion in assemblies other than compressors, such for instance vacuum orexhaust pumps and pressure pumps for gases, air or liquids and that inthe use'of the word compressor it is intended to include all otherpossible machines other than the preferred embodiment of the inventionherein shown and described as a compressor. In other words it should beunderstood that the invention and its various novel features are notlimited merely to compressors for use in refrigerating systems.

To attain the objects and benefits of the invention, a pump orcompressor embodying the invention and improvement, comprises thevarious features, combinations of features and details of constructionhereinafter described and claimed.

In the accompanying drawings forming part of this specification, and inwhich a preferred form of the invention is fully illustrated:

Fig. 1 is a vertical, central section, having parts broken away for moreclearly showing the invention and taken on the line |l of Fig. 2;

Fig. 2 is a top plan view of the compressor shown in Fig. 1;

Fig. 3 is a fragmentary, horizontal section on the line 33 of Fig. 1;

Fig. 4 is a vertical, central section or the rotating parts of thecompressor and taken substantially on the line 4-4 of Fig. 11;

Fig. 5 is a section similar to Fig. 4; but taken on the line 5-5 of Fig.10;

Fig. 6 is a bottom perspective view of the upper head of the compressorcylinder;

Fig. 7 is a top perspective view of the compressor rotor;

Fig. 8 is a bottom perspective view of the lower cylinder head of thecompressor cylinder;

Figs. 9, 10, 11 and 12 are horizontal sections on the lines 89, lib-l0,lI-ll and l2l2 respectively of Fig. 4;

Fig. 13 is a perspective view of a compressor shaft;

Fig. 14 is a fragmentary section of the lower cylinder head on the lineI l-l4 of Fig. 12;

Fig. 15 is a fragmentary'horizontal section on the line l5--I5 of Fig.1; and

Figs. 16 and 17 are fragmentary vertical sections on the lines l6l6 andl'l-ll respectively of Fig. 15.

The complete compressor, shown in the drawings comprises a rotarycompressor A, an electric motor B of peculiar construction and a casingor dome C within which the compressor and motor are enclosed. The casingis circular in horizontal, cross section, the compressor is arranged ona vertical axis located centrally .of the casing and the motor isarranged encircling the compressor andbetween the compressor and thecircular wall of the casing. Thisarrangement of the compressor and themotor results in many important advantages and results among which are';the possible provision of adequately strong and rigid bearings for thecompressor located close to the compression cylinder at each sidethereof, thus enabling the eliminatlon of any flexure of parts due tothe high pressure and forces involved and also the reduction of overalldimensions to a minimum especially as to height as the compressor andthe motor are in effect concentric with each other andonly requireheight suflicien for the compressor.

While the drawings show the compressor as being built with a verticallyarranged shaft it should be understood that the invention is notpart ofthe limited to such construction, it simply means, that at this time itis considered that this form is the preferred form, as it obviously hasadvantages over a form in which the compressor would be provided with ahorizontally disposed shaft.

The compressor A comprises a cylinder 20 arranged on a vertical axis andclosed at its upper end by a head 2| having a flat inner surface 22 andsecured to the cylinder 20 by bolts 23.

The cylinder is closed at its lower end by a similar head 24 having alike flat inner surface 25 and is secured'in place by bolts 26.

The cylinder has a cylindrical concentric bore 21 extending straightthrough from end to end and which bore is closed at its ends by theheads 2| and 24.

Within the bore 21 is' arranged a rotor or r tary piston or core 28,which is of equal ength with the cylinder and has flat upper and lowerends 29 and 30 opposed to the flat inner faces of the cylinder heads.

The rotor 28 is mounted on a vertical shaft 3| and is rigidly securedthereon to rotate therewith, by any suitable means, such as a radial setscrew 32, see Fig. 4.

The compressor shaft 3| is arranged eccentric to the cylinder 20 andconcentric in relation to the rotor 28, as best shown in Fig. 3 and thediameters of the rotor 28 and the cylinder bore 21 are such that theouter cylindrical surface of the rotor is tangential to the cylindricalsurface of the boreat one side of the cylinder as shown at 33, Fig. 3,thus providing a crescent shaped space 34 between the rotor and thecylinder and extending from end to end of the cylinder and whichconstitutes the pumping or compression space of the compressor. Theeccentricity is incheated on Figs. 4 and by the two dot and dash centerlines shown thereon.

The casing C within which the compressor A and motor B are arranged ismade fluid-tight and has a cylindrical side wall 35 closed at, its

, bottom by an integral wall 36 and closed at its top by a removablehead 31 secured to a peripheral flange 38 on the wall 35 by bolts 39. Asuitable packing 48 is interposed between the flange 38 and head 31 tomake the casing pressure-tight. As'shownthe wall 35 is provided withheat-radiating ribs 4| and the head 31 is provided with similarheat-radiating ribs 42 to assist in dispersing the heat produced whenthe compressor is operating.

Centrally disposed on the lower head 36 and rising within the casing isa bearing member 43 provided with a central bore 44 in which a bearingsleeve-45 of suitable metal, is fixed. I

The lower end 46 of the compressor shaft 3| is mounted for rotationwithin the bearing sleeve 45. The bearing member 43 is provided with acircular base 41 and the-lower head 36 of the casing is provided with acircular depression 48 concentric with the casing wall 35 and in whichthe base 41 fits andit is rigidly secured in place by bolts 49. Abearing member 58, similar to the bearing member 43 is arranged in theupper part of the casing and is provided with a vertical bore 5| inaxial alignment with the bore 44 of the lower bearing member 43 andwithin (in a bearing sleeve) which the'upper end 52 of the compressorshaft is mounted for rotating. This bearing will be described more fullyhereinafter. The

- two bearing members 43-and 58 serve to rotat- ;ably mount the rotor28.

cumferential horizontal shoulder 51 on the bearing member 43 and anouter opposed bearing ring 58 and a row of suitable bearing balls 59interposed between the two rings. The two rings 55 and 58 are providedwith ball runways 68 and 6| respectively and the outer ring 58 issupported by the inner ring 55 through the medium of the row of bearingballs 59.

The outer bearing ring 58 is secured concentrically to the lowercylinder head 24 by means of a ring 62 which is Z-shaped in crosssection.

This ring has a vertical peripheral flange 63 within which the lowercylinder head 24 is received and doweled and an inner depending verticalsleeve-like part 64 within which the outer bearing ring 58 is receivedand an inner circumhead 24 is secured rigidly to the Z-shaped ring andrests upon the upper edge of the outer bearing ring 58. The inner flange65 of the Z-shaped ring prevents the cylinder rising if there should beany tendency to'do so.

The upper ball bearing 54 comprises an inner bearing ring 61, an outer'bearing ring 68 and an interposed ring of bearingballs 69. These ringsare secured in place similarly to the rings of the lower ball bearing53, the inner ring being fitted upon the inner end 18 of the upperbearing member 50 and the outer bearing ring being secured upon the topof the upper cylinder head 2| by a Z-shaped securing ring 1|. TheZ-shaped ring 1| is secured upon the cylinder head 2| by the cylinderhead bolts 23.

The upper bearing member 50 is secured to and held in place by ahorizontal supporting plate 12 which in turn is held concentrically inposition by a concentric bore 13 of the casing within which the plate 12fits, the bearing member fitting within a central shallow depression 14in the under side of the plate 12 by bolts 15.

As stated before the motor B surrounds the compressor A and as shown,the motor B comprises a laminated inner rotor member 16 within which thecylinder 20 is concentrically arranged and upon which the rotor 16 isrigidly secured, and an outer laminated, concentrically arranged stator11. The casing is provided with a concentric bore 18 in which the stator11 is received and is held, in concentric relation with the rotor 16 butrotatably free therefrom as indicated by the airgap 19. Field coils arecarried by the stator.

The stator rests upon an inner circumferential horizontal shoulder 8| onthe outer wall of the casing and is held firmly down on same by a metalring 82 which fits within the lower part of the bore 3 above the bore 18and which is of slightly larger diameter for convenience in assembly.The ring 82 fits tightly in the bore 82 and when pushed down upon thestator is frictionally held in position. The ring 82 is wide enough torise high enough to receive and support the plate 12 to which the upperbearing member is secured. The plate 12 is doweled to the ring 82 and issecured thereto by bolts 83.

The upper bearing 50 being thus positioned vertically through the mediumof the stator 11, the ring 82 and the plate 12 a slight clearance isprovided at thevupper edge of the inner ball bearing ring 61 of theupper ball bearing 54 as shown at 84 to eliminate any possibility of thecompressor being bound vertically.

The compressor is, as has been explained, freely rotatable upon thelower ball bearing 53 and the horizontal shoulder 55 on the lowerbearing member 43.

The lower cylinder head 24 is provided with a central concentric opening85 which receives a flange 86 formed on the upper end of the bearingsleeve 45, said flange being eccentric of said sleeve equal to theeccentricity of the rotor 28 and cylinder 20 and the sleeve 45 is heldagainst rotation by any suitable means.

Slight clearance is provided between the upper surface of the flange 86and the opposed surface of the rotor 28 to avoid any possibility offriction at this point.

The upper cylinder head 2I is provided with a central concentric opening81 just large enough to clear the compressor shaft 3| which is of courseeccentric to the cylinder and said opening 81.

Operating electric current is supplied to the motor by connections 88which enter through the wall of the casing, through insulation tubes andthe connections are sealed to prevent the passage of fluids either intoor out of the casing past. the connections. It is not thought necessaryto illustrate such connections more than to indicate them as shown onFig. 2. Although an A. C. type of motor is shown, it goes without sayingthat the invention is not thus limited but that any suitable type ofmotor can be used within the scope of the appended claims.

The cylinder 20 is driven by the motor B and the compressor rotor 28 isdriven by the cylinder 20. For this purposa as best shown in Fig. 11,

a radial vane 89 is provided fixed in the wall of to the eccentricrelation of these two parts and there is provided a simple means forpreventing leakage past the vane 89 at its inner edge and the rotor.

This means comprises a cylindrical plug 92 fitting in a longitudinalbore 93 arranged near the outer cylindrical surface of the rotor 28 andopening at its outer side into the crescent shaped space 34. The plug 92is provided with a radial slot 94 in which the inner edge portion of thevane 89 fits and can move radially in and out as the compressor isrotated. This construction provides a flexible driving connectionbetween the cylinder 20 and the rotor 28 and which can readily be madepressure tight in operation.

The cylinder and rotor rotate in the direction of the arrow 95 on Fig.11. A discharge opening 96 is provided in the lower cylinder head 24 andthis opening is at the forward side of the vane 89. The gas to becompressed by the operation of the compressor is delivered to thecrescent shaped space 34 through a substantially radial passage 91 inthe rotor 28 which connects with a radial passage 98 in the compressorshaft 3|, which in turn connects with a longitudinal passage 99 extendeddown from the radial passage through the lower end of the shaft. Inorder not to make the radial passage 99 in the shaft too large thisradial passage in the shaft and the rotor may be duplicated, as bestshown in Fig. 4.

As shown in Fig. 1, the lower bearing member 43 extends down into acentral pocket I00 in the base and the lower end of the shaft 3|projects down into this pocket, the lower end of the shaft beingchambered as shown at I01 and the passage 99 enters the chamber IOI atits top. The pocket I00, in the base, is connected by a radialhorizontal passage I02 through the metal of the base to a threadedopening I03 to which a supply pipe can be connected when the compressoris used for compressing gases other than free air. The pocket I00 issealed against the entrance of oil from the lower part of the casing bythe base 410i the bearing member 43.

Through the entrance passages 91 entering the compressor behind the vane89, the gases I fill the space as the cylinder rotates and arecompressed and forced out through the discharge opening 96. Thedischarge opening 96 is controlled by a valve I 04. The lower cylinderhead 24 is provided with a shallow recess I05 to contain the valve I04which as shown comprises a fiat strip of spring metal extending over theopening 96, see Fig. 14, and a second strip I06 of similar metal and thestrips clamped to the head 24 by screws I01. The strip I06 is rounded upbetween its ends so that its free end is yieldingly pressed against thefree end of the strip I04. This construction provides a very efficientcheck valve which effectively prevents the return to the cylinder of anyof the expelled gases. The compressed gases are discharged into thecasing C and accumulate in'the casing. To permit the escape of thecompressed gases from the casing the plate 12 is provided with manyopenings I08 which permit the gases to escape freely into the space I09above the plate and beneath the cover 31. At one point the cover 31 isprovided with an opening IIO through which the compressed gasses can bedischarged for use through any suitable pressure controlling valve whichmay be adjusted to permit the discharge of the compressed gases at thedesired pressure.

Another feature of the invention relates to automobile means ofsupplying ample lubrication to all of the bearings of the compressor forreducing friction and to all of the opposed movable surfaces to sealsuch spaces and increase the efliciency of the compressor.

The lower part of the casing provides a storage space-for a supply ofoil as shown at III and I provide means operated continuously, while thecompressor is operating, for lifting oil from this supply and forcing itto the various points where it is required for lubrication and sealingpurposes.

For lifting and forcing the oil I provide an auxiliary pump whichcomprises an inner extension H2 at one end of the vane 89, best shown inFig. 4, which is the operating vane of the auxiliary pump. Thisauxiliary vane extends radially inward into a crescent shaped space II3formed at the upper end of the rotor 28.

The rotor as shown is provided with a conthe cylinder and the recess H4is concentric with the rotor and they are so proportioned that the outersurface of the rib H5 is tangential to and in. contact withvthe opposedsurface of the recess H4 at one point as shown at H6 Fig. thus formingthecrescent shaped space H3 through which the auxiliary vane H2 sweepsas the compressor is rotated.

To feed the oil from the supply H I to this space I provide a passage II8 which extends longitudinally up through the shaft 3| from a pointnear its lower end to the height of the auxiliary pump where it isconnected to the auxiliary pump space H3 by an upwardly inclined passageH9 extending out through the shaft 3| and the adjacent part of the rotor28 and ending just beyond the inner wall of said space H3. The lower endof the longitudinal passage I I8 connects with a substantially radialfeed passage I20 which connects it with a circumferential groove I2|formed in the outer surface of the shaft 3|.

The oil is fed to this groove |2| and passage I20 from the base of thecasing through a passage I22 in the lower bearing member 43 and thebearing sleeve 45 and the inner end of which registerswith the groove|2|. A feed tube I23 connects the feed passage I22 with an oil strainerI24 submerged in the oil body I I I. The oil strainer I24 comprises atubular ring I24 and to which the feed tube I23 is connected. The ringI24 is provided with many small inlet openings I25 on its inner side andthe ring is covered with a fine wire. mesh strainer I6 to prevent anyforeignv particles entering the oiling system.

The deliveryof the oil from the auxiliary pump space H3 is mainlythrough a small opening I21 extending through the. inner wall of thepump space and. adapted to deliver the oil into the space '81 within therib H5.

The oil is thus delivered into contact with the shaft 3| in the space81.

The oil also is delivered from the auxiliary pump out between theadjacent end of the rotor and the inner surface of the upper had thusassisting in sealing the compressor space at this point. The oil isfurther delivered along the surfaces of the parts which form theflexible connection between the cylinder 20 and the rotor 28.

The bearing member 50 has an upward extension I28, the cover 31 beingprovided with a hollow dome I29 into which the bearing extends. Thisconstruction admits of the maximum length of bearing without increasingthe height of the compressor. The bearing member 50 is provided with. abearing sleeve I30 of suitable bearing metal within which the shaft 3|is received and rotates. The inner surface of the sleeve is providedwith a spiral oil groove I3| which opens at its lower end into the space81 and is open at it supper end to permit the oil to escape into theinterior of the pump casing. The oil is thus fed through the wholelength of the bearing and the oil that escapes from the upper end of theoil groove |3I flows down around the upper projection I28. The plate 12is provided with a central opening I32 which forms a pocket I33surrounding the base of the projection I28 to receive the excess oil andsaid pocket is provided with a drain hole I34 extending down through thebearing member 50 and directing the excess oil back into the interior ofthe casing.

The top surface of the. top cylinder head 2| is provided with a shallowrecess I35 which extends from the center opening 81 and is large enoughin diameter to extend out to the ball bearings 54. The oil is thusdelivered to the ball bearing 54 and any surplus oil works through theball bearings out into the casing.

To direct oil to the lower end of the rotor 28 and to the lower bearingthe shaft 3| is provided in its outer surface with a longitudinallyextending oil groove I36, the upper end of which extends into the oilspace 81 and the lower end of which extends slightly below the lower endof the rotor 28.

For delivering oil to the lower end of the rotor to lubricate theopposed flat surfaces of the rotor 28 and the lower head 24, an inclinedoil feed passage I31 (Fig. 11) is provided extending through the body ofthe rotor the upper end of which connects with the groove I36'and itslower end connectswith a substantially concentric groove I38 formed inthe lower flat end 30 of the rotor. Preferably the groove I38 is not acomplete circular groove and the oil is delivered to the groove near oneend of the groove and, the other end being closed, the pressure underwhich the oil is delivered causes it to fill the groove and be forcedout radially between the opposed flat surfaces of the rotor and thelower head thus not only effectively lubricating these parts but alsoeffectively sea-ling this point against The pocket I40 is connected toan oil feed passage 42 which extends out through the sleeve flange 86and delivers oil within the recess between the edge of the flangeand'the'adjacent surface of the lower cylinder head 24. The excess oilworks down between these surfaces to the lower side of the cylinder headwhich, similar to the upper head, is provided with a shallow recess I43which extends from the inner recess 85 out to the ball bearing 53, theexcess oil es caping through the ball bearing to collect in the bottomof the casing.

The pocket |4| connects with'the upper end of a spiral oil feed grooveI44 formed on the inner surface of the bearing sleeve-45. The lower endof the groove I44 connects with a substantially radial oil passage I45formed in the body of the lowerbearing member 43 and the outer end ofwhich connects with a delivery tube I46 which delivers the excess oilinto the base of the casing.

The compressed gases which rae forced past the che'ck valve I04 escapefreely through the ball bearing 53 into the interior of the casing andas has been explained through the openings I08 in the top plate 12 intothe space I09 andfrom this space through the delivery opening H0.

As the oil is discharged, as has beenexplained, at several points, fromthe compressor there will naturally be more or less particles of oilfloating in the gases within the casingand I,preferably'- provide alarge number ofthe openingsv I08 through the top plate 12-mainly toreducethe speed of the gases through. these openings and I provide afine wire gauze filter I41 secured on the under side ofthe plate 12 andcovering said openings to assist in filtering out the oil carried 'bythe gases.

The large area of escape thus provided prevents any clogging thereof toprevent the free escape of the gases and so reduces the rate of flowthat the oil clings to the screen and drops back into the casing.Furthermore the many holes I08 serve to appreciably reduce the weightofthe plate l2. I

From the drawings and the foregoing description it will now be clearthat by means of this invention I am enabled to provide a compressor ofminimum height, commensurate with the capacity thereof, and one whichcan be operated efi'iciently practically continuously.

As many modifications of the invention 'will obviously suggestthemselves to one skilled in the art I do not limit or confine theinvention to the specific details of construction except within thevscope of the appended claims.

Throughout the specification and the appended claims, the term positivedisplacement pump is used in the sense that it defines a pump which iscapable of building up a relatively high head pressure, such for exampleas a gear pump, a reciprocating pump, a rotatory pump with one or morecomprising a. blade rigidly secured to the same member to which the endplates are secured and having a sealed fit with said member and said endplates, said blade having a sliding and rocking engagement with theother member, means for driving the blade through one of the elementsrigid therewith to produce a pumping action, bearing supports for thepump members, and for at least one of said pump members on both sidesthereof at points farther apart than-the width of the pumping chamber,a. lubricating and gas sealing system associated with the compressorincluding means adapted to deliver oil to said infinitesimal endclearances in suflicient quantity and at a pressure at least in excessof dome pressure to effectively seal said clearances against gasleakage, said cylindrical member being driven by a rotary motorsurrounding the cylindrical member and substantially centered in thecenter plane of the cylindrical member, the rotor of the motor beingcarried by the cylindrical member and supported by its bearings.

2. In a compressor, an air-tight dome, pump members within the domeincluding a rotatable hollow cylindrical member, a core member mountedtherein in eccentric tangential relation for rotation about its owncenter, and end plates rigidly secured to one of said members and havinginfinitesimally small and clearances with the other to form a pumpchamber, means dividing the chamber into intake and discharge sectionscomprising a blade rigidly secured to the same member to which the endplates are secured and "having a sealed fit with said member and saidend plates, said blade having a sliding and rocking v engagement withthe other member, means for driving the blade through one of theelements rigid therewith to produce a pumping action, bearing supportsfor the pump members, and for at least one of said pump members on bothsides thereof at points farther apart than the width of the pumpingchamber, a lubricating and gas sealing system associated with thecompressor including means adapted to deliver oil to said infinitesimalend clearances in sufiicient quantity and at a pressure at least inexcess of dome pressure to effectively seal said clearances against gasleakage, said cylindrical member being driven by a rotary motorsurrounding the cylindrical member and substantially centered in thecenter plane of the cylindrical member, the rotor of the motor beingcarried by the cylindrical member and supported by its bearings, saidbearings being of a rolling type.

3. In a compressor, a gas-tight dome, pump members therein including arotatable hollow cylinder and a rotatable core mounted in eccentrictangential relation thereto, each being rotatable about its own center,end plates closing the space between the members to form a pump chamber,a blade dividing the chamber into intake and discharge sections, the endplates and blade being rigidly secured to one of the members, the endplates having infinitesimal clearances with the other member, and theblade sliding in a rocker in said other member and having at least aportion extending at all times at least to the pivotal axis of therocker, means for driving the rigid assembly including the end platesand blade and through the blade driving said other member, bearings forone of said members on both sides thereof and bearing means for theother'member restraining it from canting, and

means for sealing and lubricating said infinitesimal clearancesincluding a. secondary pump within the dome and including a secondarycylinder and a secondary core formed between the main coreand an endplate adjacent thereto, with the cylinder formed as a recess in one ofsaid lastnamed members, and the secondary core formed as a boss integralwith the other of said lastnamed members, said secondary pump beingconstructed and arranged to deliver oil to said infinitesimal clearancesin sufficient quantity and at a pressure at least in excess of the pumpchamber pressure to effectively seal said clearances against gasleakage.

WM. WARD DAVIDSON.

